Biomedical subjects

M Jeremic

Publications and source records attributed to M Jeremic.

At least 19 recordsLinked to original sources

PubMed2001

Topographical characterization and surface force spectroscopy of the photochemical lignin model compound.

By combining the results from atomic force microscopy (AFM) and environmental scanning electron microscopy (ESEM), herein we investigate properties of photochemical lignin model compounds. We provide evidence that photochemical lignin forms random, probably non-functional structures. The topography of such structures is explored using ESEM. Non-functionality of such structures is proved by AFM and atomic force spectroscopy experiments wherein the photochemical lignin functionalized tip is approached to the substrate covered with photochemical lignin. There was no evidence of existence of any kind of host-guest interaction during the approach/retraction experiments. These results provide evidence for our previously stated hypothesis that photochemical lignin polymerization may be one of the degrading effects of UV radiation to the plant cell.

Dimerization↗

PubMed2000

A Comparative Study of Enzymatically and Photochemically Polymerized Artificial Lignin Supramolecular Structures Using Environmental Scanning Electron Microscopy.

Environmental scanning electron microscopy images of the self-assembled structures of enzymatically (DHP) and photochemically polymerized (PCP) artificial lignin are herein presented. Differences in the structural organization between DHP and PCP polymer at the supramolecular level were reported. Based on topological information, we proposed a hypothesis about possible new physiological roles of lignin in live plant cells and the ecological significance of possible in-vivo photochemical lignin polymerization. Copyright 2000 Academic Press.

Journal Article↗

PubMed2000

Visualization of artificial lignin supramolecular structures

In this paper we are presenting the results of our environmental scanning electron microscopy (ESEM) investigation of the lignin model compound--enzymatically polymerized coniferyl alcohol, also known as dehydrogenate polymer (DHP). The goals of this study were to visualize the supramolecular organization of DHP polymer on various substrates, namely graphite, mica, and glass, and to explore the influence of substrate surface properties and associated collective phenomena on the lignin self-assembled supramolecular structure. Based on results obtained with ESEM, combined with previously published results based on scanning tunneling microscopy (STM) and electron spin resonance (ESR) technique, we looked at lignin structure ranging from a monomer on a fraction of nanometer scale to a large aggregate on a fraction of millimeter scale, therefore using six orders of magnitude range of size. Herein, we are presenting evidence that there are at least four different levels of the supramolecular structure of lignin, and that its supramolecular organization is well dependent on the substrate surface characteristics, such as hydrophobicity, delocalized orbitals, and surface-free energy.

Journal Article↗

PubMed1983

Functional and antigenic antithrombin III values in plasma and serum from 115 regular blood donors and antithrombin III in prediction of postoperative thrombosis.

Antithrombin III (AT-III) was determined functionally using chromogenic substrate (S-2238) and immunologically using radial immunodiffusion (RID) in plasma and serum from 115 blood donors. There was a decrease in functional activity by 43.5% and in antigen concentration by 18.4% during in vitro coagulation when corresponding serum and plasma samples were compared. A positive correlation was found between the two methods in plasma (r = 0.784) as well as in serum ( r = 0.658). RID in serum correlated well with RID in plasma (r = 0.811), but the correlation for S-2238 in plasma and serum was poor (r = 0.411). Functional AT-III decrease during coagulation was uncorrelated with age and fibrinogen, and was not statistically affected by sex, smoking or blood groups. Preoperative functional AT-III activity was measured in 25 patients undergoing elective hip replacement, 60% of whom developed postoperative thrombosis. The functional activity in serum discriminated well between the thrombotic and nonthrombotic group of patients (p less than 0.025), whereas the activity in plasma showed only a minor difference.

Adolescent↗

PubMed1980

An attempt at predicting postoperative deep vein thrombosis by preoperative coagulation studies in patients undergoing total hip replacement.

Preoperative levels of fibrinogen, factors V, VII, VIII and antithrombin III were measured in 25 consecutive patients undergoing total hip replacement. Deep vein thrombosis (D.V.T.) was detected by fibrinogen-uptake test in 60% of the patients. The preoperative fibrinogen level was significantly higher (p < 0.05), and serum antithrombin III was markedly lower (p less than or equal to 0.1) in patients with postoperative D.V.T. The quotient of fibrinogen to serum antithrombin III was significantly higher (p < 0.01) in patients with D.V.T. This quotient may serve as an additional parameter to other clinical and laboratory tests in prediction of postoperative D.V.T. following hip surgery.

Aged↗

PubMed1976

Factor VIII (AHG) levels in 1016 regular blood donors. The effects of age, sex, and ABO blood groups.

Factor VIII (AHG) activity was assayed in the plasma specimens from 1016 regular and controlled blood donors. Age and ABO blood groups had highly significant effects on factor VIII concentrations, whereas the effect of sex was not significant. The median in the donors of blood group O rose from 87% at the age of 20 to 119% at the age of 60 years, and the median in blood groups A and B+AB of corresponding ages rose from 108 to 147%. An interaction effect of age and blood groups was present only at the 5% level of significance. The present data and the previous findings of others suggest the existence of an association between high factor VIII levels and thrombotic states.

ABO Blood-Group System↗

PubMed1975

Factor V (proaccelerin) concentration in 1016 blood donors. The effects of age, sex, and ABO blood groups.

Factor V (proaccelerin) concentration was measured in the plasma of 1016 regular and controlled blood donors. Age had a highly significant effect on factor V concentration. The median rose from 99 per cent at the age of 20 to 123 at the age of 60 years. Minor effects of sex and ABO blood groups were suggested. Interactions between these factors were found negligible. Accuracy and precision of the assay method and the use of percentiles in the laboratory reports are discussed. The results may support the hypothesis of relation between high concentration of coagulation factor V and predisposition to thrombosis.

ABO Blood-Group System↗

PubMed1974